Wait until your character is at least somewhat leveled up.
Plug in a second controller and begin a co-op game without using a second profile.
Using the second controller, go to your henchman's abilities and discard all of them, returning the experience to the pool. Then quit out of the co-op game.
You should find that all the "leftover" experience has been transfered to your hero.
Repeat ad nauseum.
*Note: Your co-op henchman will have the same abilities that you do, so the stronger the hero the more abilities there are to sell off and thus more experience.

Once you get into Bowerstone Market walk to Town Square.
Once there you will find a potion shopkeeper on the left hand side. Walk around the right side of the buildings there and down an alley to find a house known as Monster Manor. Sleep in this manor to gain its benefit (+1 star of Physique)
Once you gain this benefit, go to your abilities list, select physique and hit Y to unlearn it.
You will find that the bonus star from the house does not disappear, but the experience is given to you anyway. You can repeat this process over and over, the more stars you have in physique the more exp you get each time. This experience is general experience and can be applied to any skills.

In the side quest "Treasure Island of Doom", the Lionhead Studios Lion can be found once you get to the treasure island. Look at the island in the middle of the lake and it is in the shape of the Studio's Lionhead logo.